I assume the fact it is a third party application means debugging gets harder, and the business case for doing so is weaker/none.

But I would hope that some kind of reverse debugger triggered on one of these crashes would make it pretty simple to say "who wrote this 01".

Part-2 is more than a paragraph and is logically distinct from Part-1. In this, Raymond actually gets the crucial clue from another colleague's debugging efforts which leads him to identify that the bottom byte of HMODULE of the DLL gets overwritten by <something> which is the root cause of the bug; viz.

The “DLL unmapped from memory” crash is just an alternate manifestation of the “somebody is writing 01 bytes to places they shouldn’t” bug. The original bug had a larger bucket spray than we initially thought.

Part-2 is the essence of the solution while Part-1 is a series of investigations and inferences.

Might have been an “I need to look into this” segueing into “ never mind”?

Or, as the original article suggests, blame someone else.

Oh man, my journey from idealistic “there is always an explanation” youth to “some days it do be like that, and we may never know why” in a nutshell.

I am, for 20 years now. I do embedded stuff too. Still.

Looking more closely would resolve it one way or the other.

It's not, by the article, in a strict taxonomy.

In a wider sloppier sense some use the term for bugs that are hard to pin down and exhibit wide behaviours.

It basically is that. It's a standardized sticks and stones. Plus objects for some reason. But I don't think the objects are a bad thing - it allows multiple implementations of sometimes to co-exist - consider using two different GPUs from different vendors at the same time. It took a really long time and a bunch of hacks to make OpenGL support that, but DirectX could always do it (at least at the API level) by just creating two different ID3DDevice objects backed by different code from different DLLs both loaded at the same time.

OpenGL basically loads the GPU driver DLL that directly implements the OpenGL functions while Direct3D uses a COM object with a vtable so it can easily have two different ones.